Principles of Surface Chemistry Central To the Reactivity of Organic Semiconductor Materials

Organic thin-films are rapidly becoming implemented as semiconducting materials in electronic devices and as a result, surface reactivity plays an increasingly important role in the improvement of semiconducting properties. My dissertation addresses how organic thin-films react with gaseous molecules. Previous reports of chemical reactions on organic surfaces claim, “phase rebuilding reaction mechanisms,” whereby reactions only proceed if chemisorbed adsorbate molecules are able to traverse through voids in the molecular lattice. The over-assumptions of this model and lack of correlation to reaction temperature make understanding of organic substrate reactivity incomplete. In contrast, I argue applied heat causes deformation of the molecular lattice during reaction thus voids in the molecular lattice cannot be the sole basis for reactivity. Further, I correlate reactivity in solution phase to the solid state in order to determine the driving force of reactivity (lattice energy or chemical structure). My dissertation reveals the uniqueness of reactivity of organic substrates while drawing connections to traditional surface chemistry. Lastly, the role of defects in inducing the reactivity of otherwise unreactive surface was evaluated. Surface-sensitive spectroscopy and topological analysis was performed using techniques such as PM-IRRAS, XPS, AFM, SIMS and optical microscopy were used to monitor the reaction. The results present a sizable step towards the realization of improving interfaces in organic electronics